The present invention relates to switching power conversion circuits.
Electronic devices require voltage and current to operate. Generally, different electronic devices and systems have different voltage and current operating requirements. For example, some devices require a 3.3 volt supply voltage that is capable of providing up to 100 mA, and other devices require a 5 volt supply voltage that is capable of providing 1 A of current or more. Power is often provided from wall sockets or batteries that supply standard voltages and currents. Wall sockets typically provide 110 volts of AC power, and batteries provide a wide range of voltages as DC power. Accordingly, to bridge the gap between voltages and currents provided by power sources, such as wall sockets or batteries, and the voltages and currents required by different electronic devices, such as cell phones or computers, power conversion circuits are desirable.
One class of power conversion circuits includes switching power conversion circuits. Within this category there are two different types of configurations (or modes) for power conversion circuits—boost mode and buck mode. In boost mode, the output voltage is greater than the input voltage. Conversely, in buck mode, the input voltage is greater than the output voltage.
Switching power conversion circuits typically include at least one inductor for storing energy, a switch for periodically recharging the inductor, and a filter (typically a capacitor) to filter out noise from the switch. A typical switching power conversion circuit monitors output voltage and/or current levels, and generates a feedback signal. The feedback signal, in turn, is used to generate a pulse width modulated (PWM) signal for turning the switch on and off. Many power conversion circuits are configured to maintain the output voltage at a constant level across a range of output currents.
Switching power conversion circuits typically operate using feedback signals to monitor the output. Because existing techniques require monitoring of the output, extra dedicated pins on an integrated circuit are typically required to receive the feedback inputs.
Switching power conversion circuits are typically implemented using analog circuits. Analog circuits typically occupy larger areas of silicon, which increases costs. Additionally, external switches occupy external space and adds cost on the system.